JP4840047B2 - Image display device and projector - Google Patents

Description

  The present invention relates to an image display apparatus and a projector that display a multi-gradation image, and more particularly to an image display apparatus and a projector that are suitable for high gradation display.

In recent years, image quality improvement in electronic display devices such as LCD (Liquid Crystal Display), EL (Electroluminescence Display), CRT (Cathode Ray Tube), and projection display devices has been remarkable, and the resolution color gamut is almost comparable to human visual characteristics. Devices with performance are being realized.
However, with respect to the luminance dynamic range, the reproduction range is at most about 1 to 10 ² [nit], and the number of bits expressing the gradation is generally 8 bits.
On the other hand, human visual perception has a range of luminance dynamic range that can be perceived at a time of about 10 ⁻² to 10 ⁴ [nit] and a luminance discrimination capability of 0.2 [nit], corresponding to this luminance discrimination capability. If the range of the luminance dynamic range is converted into the number of gradations, it is said that a data amount corresponding to about 12 bits is required.

When viewing the display image of the current electronic display device via the visual characteristics as described above, the narrowness of the luminance dynamic range is conspicuous, and in addition, the resolution of the gradation of the shadow part and the highlight part is insufficient. , You will feel unsatisfactory with the reality and power of the displayed image.
In addition, in CG (Computer Graphics) images used in movies, games, etc., the movement for pursuing the reality of depiction by providing data with a luminance dynamic range and gradation characteristics close to human vision is becoming mainstream. is there.
However, since the performance of the electronic display device is insufficient, when the image of the CG content is displayed, the image expressive power (the number of bits for expressing gradation) that the CG content originally has is sufficiently exhibited. There is a problem that can not be done.

Furthermore, in the next Windows (registered trademark), the adoption of a 16-bit color space is planned, and the dynamic range and the number of gradations are dramatically increased as compared with the current 8-bit color space. For this reason, it is considered that there is an increasing demand for realizing a high dynamic range and high gradation electronic display device capable of fully utilizing the 16-bit color space in CG content.
Among display devices, a projection display device (projector) such as a liquid crystal projector or a DLP (Digital Light Processing (trademark)) projector can display a large screen and is effective in reproducing the reality and power of a display image. A display device. In this field, the following proposals have been made to solve the above problems.

As a display device with a high dynamic range, the contrast ratio is adjusted by double-modulating illumination light from a light source with two light modulation elements (first light modulation element and second light modulation element) arranged in series on the optical path. An HDR (High Dynamic Range) display has been proposed as a two-modulation projection display device to be improved. (For example, refer to Patent Document 1).
In such an HDR display, each of the red illumination light, the green illumination light, and the blue illumination light is modulated by the first light modulation element and then synthesized using a cross dichroic prism (synthesizing means). The combined light is further modulated by the second light modulation element.

In the two-modulation projection type display device described above, moire is likely to occur due to the lattice structure of each of the first light modulation element (arranged in the previous stage) and the second light modulation element (arranged in the subsequent stage). It is possible to suppress the occurrence of moire by increasing the magnification accuracy and alignment accuracy of the optical system.
In addition, in the two-modulation projection display apparatus, in order to appropriately drive the first and second light modulation / modulation elements in accordance with the input signal, a two-modulation process for obtaining a control value corresponding to the gradation is required. .

For example, as shown in FIG. 7, the two modulation processing is control for increasing the transmittance of both the first and second light modulation elements as the input signal increases. FIG. 7 shows an example of the transmittance of each of the first and second light modulation elements in the two-modulation process performed on an 8-bit input signal. The horizontal axis indicates the control value level, and the vertical axis The axis indicates the transmittance. By the distribution control in the two-modulation processing, even if the alignment between the corresponding pixels of the first and second light modulation elements is slightly shifted, the influence on the image quality can be suppressed.
JP 2005-250440 A

The two-modulation projection display apparatus uses a light modulation element having pixels of the same resolution and the same size as the first and second light modulation elements.
However, the modulation-type projection display device forms an image on the second light modulation element arranged at the subsequent stage due to the influence of various optical elements arranged between the first and second light modulation elements. As shown in FIG. 8, the image formed by the first light modulation element arranged in the previous stage is not sufficiently condensed and spreads larger than the size of the pixels of the first light modulation element. is doing. FIG. 8 is a conceptual diagram showing the spread of the projection light transmitted through the pixels of the first light modulation element at the second light modulation element. 8A shows the spread of R component light, FIG. 8B shows the spread of G component light, and FIG. 8C shows the spread of B component light.

For this reason, even if the optical alignment is adjusted with respect to the first and second light modulation elements so that moire is not generated in the entire white display, one vertical line as shown in FIG. When a high-frequency and high-amplitude image is displayed so that black and white alternately appear every time, a new moire is generated.
That is, if the projection light emitted from each pixel of the first light modulation element has a perfect one-to-one correspondence with the pixel of the second light modulation element, ideally the center pixel in FIG. A state in which only irradiation (image formation) is performed is desirable.
However, in reality, as shown in FIG. 7, it is unavoidable that light is spread by various optical components between the first and second light modulation elements.

When the high-frequency light amplitude image shown in FIG. 9A is displayed, as shown in FIG. 9B, R, G, and R emitted from the first light modulation element in the pixel portion displaying white are displayed. An image is formed by irradiating each of the B lights in a spread state. Here, the thicknesses of R, G, and B light indicate the amount of light per unit area, that is, the light density in the region that is spread and irradiated. Here, FIG. 9B is a conceptual diagram illustrating the three pixels indicated by the broken lines in FIG. Here, in both the first and second light modulation elements, the pixels in the white display region have a high transmittance, and the pixels in the black display region have a low transmittance.
Therefore, as shown in FIG. 9C, the amount of G and B light emitted from the white display pixel of the second light modulation element is reduced compared to the amount of R light. .

In the example shown in FIG. 9, it is shown that the G and B light components other than the R light component are relatively spread compared to the R light component.
As described above, FIG. 9C shows the state of an exit scene from the second light modulation element, because the light amount of the R light component is larger than the light amounts of the other G and B light components. Therefore, the pixel portion of white display is displayed as a slightly reddish color.
Thus, due to the difference in the spread of light of each of the R, G, and B color components, an image that is originally white is tinged.

The difference in the spread of the light of each of the R, G, and B components is not uniform over the entire screen, but is affected by the optical components arranged in the middle, and therefore nonuniformly occurs depending on the pixel position in the second modulation element. Will do.
As a result, in the conventional modulation type projection display device, the corresponding pixel alignment between the first and second light modulation elements is adjusted with high accuracy, and moiré is generated in a solid screen display such as an all-pixel white display. Even if it is controlled to be in a state where there is no image, when a high-frequency, high-amplitude image such as a checkered pattern in which black and white alternately appear for each pixel column (or pixel row), a new moiré occurs. is there.

  The present invention has been made in view of such circumstances. With a simple configuration, the light emitted from the pixel of the first light modulation element is larger than the pixel size in the corresponding pixel of the second light modulation element. An object of the present invention is to provide an image display device capable of suppressing the occurrence of moire when a high-frequency light amplitude image is displayed even in a spread state.

  In the image display device of the present invention, a first light modulation element and a second light modulation element arranged at a subsequent stage of the first modulation element are optically arranged in series in units of pixels, and an image signal is inputted. Corresponding to the above, a two-modulation optical system image display device that displays images by controlling the respective transmittances, and obtains a first light modulation element control value for driving the first light modulation element from the image signal. A first light modulation element control value determination unit; a second light modulation element control value determination unit for obtaining a second light modulation element control value for driving the second light modulation element by the image signal; and the second light modulation element From the control value, a pixel having a relatively low transmittance is detected in a region where the pixel having a different transmittance changes in a high-frequency high-amplitude state where the pixels appear alternately, and the first light modulation element corresponding to this pixel is detected. A high-frequency, high-amplitude signal detector that uses a pixel as a correction target pixel, and the complement By a first light modulation element control value correction unit that corrects the first light modulation element control value of the target pixel in accordance with the transmittance of other pixels in the region, and the corrected first light modulation element control value, A first light modulation element driving unit for driving the first light modulation element, and a second light modulation element driving unit for driving the second light modulation element according to the second light modulation element control value. .

With the configuration described above, according to the image display device of the present invention, the light emitted from the first light modulation means spreads to the pixels adjacent to the corresponding pixel without being sufficiently condensed on the second light modulation element. Therefore, in the case of high-frequency and high-amplitude image display, the emitted light corresponding to the spread is blocked by the pixels of the second light modulation element having a low transmittance, but the second light modulation element corresponding to the shielded low-transmittance pixels. By increasing the transmittance of a pixel (correction target pixel) of one light modulation element, the light emitted from this pixel spreads to adjacent high-transmittance pixels in the second light modulation element, so that the originally high transmittance is adjacent. The light emitted from the pixel of the first light modulation element corresponding to the adjacent light-shielded pixel spreads to the pixel of the second light modulation element to compensate for the amount of light reduced by the spread of light in the pixel with high transmittance. be able to.
That is, according to the image display device of the present invention, in the case of high-frequency and high-amplitude image display, the transmittance of the pixel of the second light modulation element corresponding to the pixel of the first light modulation element is greater than the transmittance of the adjacent pixels. Is sufficiently low, the amount of light emitted from the adjacent pixel of the second light modulation element having a high transmittance is corrected by increasing the transmittance of the pixel of the first light modulation element corresponding to this pixel. Therefore, compared to the conventional example, the occurrence of moire can be suppressed by simple calculation correction only by performing comparison processing.

In the image display device of the present invention, the high-frequency, high-amplitude signal detection unit detects the correction target pixel by comparing the transmittance between the detection target pixel and a pixel adjacent to the detection target pixel. It is characterized by performing.
With the above configuration, according to the image display device of the present invention, a correction target that needs to be corrected to suppress the occurrence of moire by comparing the transmittance between adjacent pixels that are most involved in the occurrence of moire. Pixel detection can be efficiently performed with high accuracy.

In the image display device of the present invention, when the high-frequency, high-amplitude signal detection unit detects the correction target image, the ratio of the second light modulation control value of the pixel to be detected and the transmittance between the pixels adjacent to the pixel. It is characterized by performing with a threshold set corresponding to the above.
With the above configuration, according to the image display device of the present invention, since the threshold is set by the ratio of the transmittance set in advance between adjacent pixels, it is possible to compare the light amount according to the transmittance value between the pixels. This makes it possible to detect the correction target pixel that needs to be corrected to suppress the occurrence of moire with high accuracy.

When the high-frequency, high-amplitude signal detection unit detects that the control value of any adjacent pixel exceeds a threshold corresponding to the control value of the detection target pixel, the image display device of the present invention detects the detection target This pixel is a correction target pixel.
With the above configuration, according to the image display device of the present invention, it is easy to determine whether or not it is necessary to correct the amount of light lost due to the spread of the pixel in the light of the adjacent first light modulation element with high transmittance. Therefore, it is possible to detect the amount of light effectively.

The image display device of the present invention has a threshold value table indicating a correspondence relationship between the second light modulation element control value and a threshold value with respect to the second light modulation element control value, and adjoins pixels for white display and black display. Display a high-frequency, high-amplitude state image, increase the transmittance of adjacent black display pixels by a certain width, determine the ratio of the transmittance when moire is no longer visible, and control each second light modulation element control value The reference transmittance is obtained by multiplying the transmittance corresponding to the ratio by the reciprocal of the ratio, and the second light modulation element control value corresponding to the reference transmittance is used as the threshold value.
With the above configuration, according to the image display device of the present invention, a threshold value can be set for each device, and it is possible to perform highly accurate control corresponding to different alignments and light collection states for each device, and Since the threshold value can be easily read and used when detecting the correction target pixel, the correction target pixel can be detected at high speed.

In the image display device according to the aspect of the invention, the first light modulation element control value correction unit may display the first light modulation element control value of the correction target pixel with the highest transmittance among pixels adjacent to the detection target pixel. To the first light modulation element control value of the pixel corresponding to the first light modulation element, or to the first light modulation element control value of the pixel showing the highest transmittance in the pixel adjacent to the correction target pixel. It is characterized by that.
With the configuration described above, according to the image display device of the present invention, the control value of the pixel of the first modulation element corresponding to the pixel of the second light modulation element having the highest transmittance that needs correction as the control value of the correction target pixel. Therefore, effective correction can be performed.

In the image display device of the present invention, the high frequency high amplitude signal detection unit uses “0” as the control value of the virtual pixel when the adjacent pixel does not exist in the pixels on the outer periphery of the image. A detection process is performed.
With the above configuration, according to the image display device of the present invention, when a pixel that does not have adjacent pixels in advance is a detection target, it is not necessary to perform an extra exception process, and thus it is not necessary to perform an unnecessary calculation process, and a correction target. Pixel detection processing can be performed efficiently.

In the image display device of the present invention, when the first modulation element is provided for each of the R, G, and B color components, the high-frequency, high-amplitude signal detection unit detects the correction target pixel in the R, G, and B colors. It carries out for every component, It is characterized by the above-mentioned.
With the above configuration, according to the image display device of the present invention, by correcting the correction target pixel for each color component, the first and second light modulation elements having different characteristics for each color component can be aligned and condensed. Correspondingly, correction with high accuracy can be performed, and generation of moire can be suppressed with high accuracy.

A projector according to the present invention includes any one of the image display devices described above and a projection unit that projects the modulated light emitted from the image display device onto a screen.
With the above configuration, according to the projector of the present invention, in the case of high-frequency and high-amplitude image display, the transmittance of the pixel of the second light modulation element corresponding to the pixel of the first light modulation element is greater than the transmittance of the adjacent pixels. Is sufficiently low, the amount of light emitted from the adjacent pixel of the second light modulation element having a high transmittance is corrected by increasing the transmittance of the pixel of the first light modulation element corresponding to this pixel. In comparison with the conventional example, it is possible to perform image display with suppressed moiré by simple calculation correction only by performing comparison processing.

  According to the present invention, light emitted from the pixel of the first light modulation element is transmitted to the pixel of the second light modulation element between the pixels optically arranged in series in the first light modulation element and the second light modulation element. In order to suppress moiré that occurs when displaying high-frequency, high-amplitude images with greatly different transmittance between adjacent pixels in the phenomenon of spreading without being sufficiently condensed, the second light modulation element has a high transmittance. The pixel of the first light modulation element corresponding to the pixel with low transmittance adjacent to the pixel is detected as the correction target pixel, and the first light modulation element of the correction target pixel is set so as to increase the transmittance corresponding to the surrounding pixels. The present invention relates to an image display device in which a control value is changed, and the amount of light emitted from a pixel having a high transmittance in the adjacent second light modulation element is complemented by the spread of light emitted from the correction target pixel.

<First Embodiment>
Hereinafter, an image display apparatus according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of the embodiment.
As shown in FIG. 1, the image display apparatus according to the present embodiment includes a first light modulation element control value determination unit 1, a second light modulation element control value determination unit 2, a high frequency high amplitude signal detection unit 3, a threshold table 4, It comprises a first light modulation element control value correction unit 5, a first light modulation element drive unit 6, a first light modulation element 7, a second light modulation element drive unit 8, and a second light modulation element 9.
Each of the first light modulation element 7 and the second light modulation element 9 is a liquid crystal display element, and the liquid crystal elements are arranged in a matrix in units of pixels.

The first light modulation element control value determination unit 1 controls the transmittance of the corresponding pixel of the first light modulation element 7 from the gradation of the input video signal (image signal) input in time series. The element control value is obtained and output to the first light modulation element control value correction unit 5.
The second light modulation element control value determining unit 2 determines a second light modulation element control value for controlling the transmittance of the corresponding pixel of the second light modulation element 9 from the gradation of the input video signal input in time series. Obtained and output to the high frequency, high amplitude signal detection unit 3 and the second light modulation element driving unit 8.
Here, the input video signal is input as, for example, the gradation of each color component of R (red), G (green), and B (blue).
Each of the first light modulation element control value determination unit 1 and the second light modulation element control value determination unit 2 includes a gradation and a control value (first light modulation element control value or second light modulation element control value) provided therein. The control value table for each pixel is retrieved, and the control value corresponding to each input gradation is read out and output to obtain the control value for each pixel.

In the configuration of FIG. 1, in the image display device, color components that are poorly aligned and condensed between the corresponding pixels arranged in series of the first light modulation element 7 and the second light modulation element 9, for example, R Only the component is subjected to the above-described transmittance correction. The first light modulation element 7 is for modulating each color component, and is provided for each color component.
In the other color components G and B, the first light modulation element driving unit 6 performs other corrections based on the numerical values of the first light modulation element control values obtained by the first light modulation element control value determination unit 1 as they are. The first light modulation elements 7 corresponding to the color components G and B that are not performed are driven.
If the condensing state of each color is the same, the same transmittance correction may be performed not only for the R component but also for the G and B components.
The above-described image display apparatus may display a high-intensity monotone image by inputting a single gradation of a monotone (monochrome) image instead of the gradation of R, G, and B as an input video signal. . In this case, there is one second light modulation element.

The high-frequency, high-amplitude signal detection unit 3 receives the second light modulation element control value of the search target pixel (hereinafter referred to as detection pixel) input from the second light modulation element control value determination unit 2 and the detection target pixel. The second light modulation element control value of an adjacent pixel (hereinafter referred to as a comparison pixel) is compared with a second light modulation element control value that exceeds a threshold value set corresponding to the second light modulation element control value of the detection pixel. When the comparison pixel having the second light modulation element control value exceeding the threshold is detected, the pixel of the first light modulation element corresponding to the detection pixel is set as the correction target pixel. .
Further, the high-frequency, high-amplitude signal detection unit 3 uses, as a comparison pixel, an adjacent pixel that has the second modulation element control value having the highest transmittance.

The threshold value table storage unit 4 corresponds to the second light modulation element control value corresponding to each transmittance in the pixel of the first light modulation element 7 corresponding to the target color component, and this second light modulation element control value. A threshold value table shown in FIG. 2 in which threshold values are associated is stored.
This threshold value is set for each individual image display device while an operator actually confirms the occurrence of moire as described below.
That is, an image in a high-frequency, high-amplitude state in which white display and black display pixels are adjacent to each other is displayed, the transmittance of the black display pixels of the second display element is increased by a certain width, and the operator generates moiré. The ratio of the transmittance of white display and black display between adjacent pixels at the time when it is no longer visible.

Then, when the occurrence of moiré cannot be visually recognized, a ratio obtained by dividing the low transmittance of black display by the high transmittance of white display between adjacent pixels is obtained. For example, if this ratio is 0.4, when the second light modulation element control value is 150, the transmittance corresponding to the second light modulation element control value of 150 is 20%. Dividing by the ratio (or multiplying by the inverse of the ratio 2.5) gives 50%. The transmittance of 50% is the reference transmittance, and the reference transmittance for each second light modulation element control value is as shown in FIG.
Further, the second modulation element control value is obtained by reversely referring to the transmittance characteristic of FIG. Since the second light modulation element control value corresponding to the reference transmittance of 50% is 198 and the control step of the second light modulation control value is “1”, 197 obtained by subtracting 1 from 198 is the transmittance 20 % As a threshold for the second light modulation element control value. Therefore, the threshold value table is as shown in FIG.

For the reason described above, in this threshold value table, the threshold value exceeding the second light modulation element control value “188” corresponding to the transmittance of 40% at which the transmittance of 100% is 0.4 of the above ratio is “255”. The search pixel having the second light modulation element control value corresponding to “255” does not need to be searched for the correction target pixel.
Therefore, the high-frequency, high-amplitude signal detection unit 3 reads the threshold value of the second light modulation element control value of the search pixel, and this threshold value is a control range of the second light modulation element control value (in the present embodiment, “0” to “0”). When it is detected that the maximum value is “255”) (“255” in this embodiment), the subsequent search for the pixel to be corrected is not performed.

The first light modulation element correction unit 5 uses the first light modulation element control value of the correction target pixel detected by the high frequency, high amplitude signal detection unit 3 as the first light of the pixel of the first light modulation element 7 corresponding to the comparison pixel. The modulation element control value is changed and corrected, and the corrected result is output to the first light modulation element driving unit 6 as the first light modulation element control value. That is, the first light modulation element control value of the correction target pixel is the first light modulation element control value of the pixel of the first light modulation element corresponding to the comparison pixel adjacent to the search pixel.
The first light modulation element drive unit 6 uses the corrected first light modulation element control value (voltage value) output in time series from the first light modulation element control value correction unit 5 to generate the first light modulation element 7. Each pixel is sequentially driven to obtain a transmittance corresponding to the control value.
The second light modulation element drive unit 8 uses the second light modulation element control value (voltage value) output in time series from the second light modulation element control value determination unit 2 to determine the first light modulation element drive unit 6. In synchronization with the drive timing of the first light modulation element 7, each pixel of the second light modulation element 9 is sequentially driven to obtain a transmittance corresponding to the control value.

Next, control value correction processing in the image display apparatus of FIG. 1 will be described with reference to FIG. FIG. 3 shows the second light modulation element control value of the search pixel of the second light modulation element 9 and its neighboring pixels, and the pixel of the first light modulation element 7 arranged in series with respect to this search pixel and its neighbors. It is a conceptual diagram which shows the 1st light modulation element control value of the pixel to perform. FIG. 3A shows the respective control values before correction, and FIG. 3B shows the control values after correction.
Here, the pixel P2 is a search pixel in the second light modulation element, and the pixels T21 to T24 are pixels adjacent to the pixel P2. The pixel P1 is a pixel of the first light modulation element corresponding to the pixel P2 that is the search pixel, and the pixels T11 to T14 are pixels adjacent to the pixel P1.

The high-frequency, high-amplitude signal detection unit 3 internally stores the second light modulation element control value input from the second light modulation element control value determination unit 2 in association with the position information of each pixel of the second light modulation element 9. Store in the department.
At this time, the first light modulation element control value correction unit 5 also uses the first light modulation element control value input from the first light modulation element control value determination unit 1 as position information of each pixel of the first light modulation element 7. And stored in the internal storage unit.
Then, when the storage of the first light modulation element control value for one frame is completed in the internal storage unit, the high-frequency high-amplitude signal detection unit 3 sequentially reads out the first light modulation element control value and outputs the corresponding pixel. Whether or not the pixel is a correction target pixel is detected.

In FIG. 3A, for example, the high-frequency high-amplitude signal detection unit 3 reads the second light modulation element control value of the pixel P2 from the internal storage unit, and uses the pixel P2 as a search pixel.
Then, the high-frequency, high-amplitude signal detection unit 3 reads the second light modulation element control values of the adjacent upper, lower, left, and right pixels T21 to T22 from the internal storage unit, and detects the largest second light modulation element control value. Then, the pixel corresponding to the second light modulation element control value, that is, the pixel T24 in FIG. 3A is extracted as a comparison pixel.

Next, the high-frequency, high-amplitude signal detection unit 3 reads the threshold value [197] for the second light modulation element control value [150] of the search pixel P2 from the threshold table, and the second light modulation element control value [of the comparison pixel T24 [ 215] exceeds this threshold value [197].
When the high-frequency, high-amplitude signal detection unit 3 detects that the second light modulation element control value [215] of the comparison pixel T24 exceeds the threshold value [197], the high-frequency and high-amplitude signal detection unit 3 obtains positional information of the detection pixel P2 and the comparison pixel T24. 1 output to the light modulation element control value correction unit 5. At this time, when the high-frequency, high-amplitude signal detection unit 3 detects that the second light modulation element control value of the comparison pixel does not exceed the second light modulation element control value of the search pixel, the first light modulation element control Control information indicating that the pixel P1 of the first light modulation element 7 corresponding to the search pixel P2 does not need to be corrected is output to the value correction unit 5.

Thereby, the first light modulation element control value correction unit 5 sets the pixel P1 of the first light modulation element 7 corresponding to the position information of the detection pixel P2 as a correction target pixel, as shown in FIG. 3B. The first light modulation element control value [150] of the pixel P1 is changed to the first light modulation element control value [176] of the pixel T14 of the first light modulation element 7 corresponding to the positional information of the comparison pixel T24.
On the other hand, when the control information indicating that the pixel P1 does not need to be corrected is input to the first light modulation element control value correction unit 5, the first light modulation element control value is not corrected. 6 is output.

Further, as shown in FIG. 4, in the case of the pixel P2 in the upper left part of the image, the high frequency high amplitude signal detection unit 3 uses the nonexistent pixels as virtual pixels T21 and T24, and the second light modulation element control value is set respectively. The search pixel that is treated as “0” and has the maximum second light modulation element control value is extracted.
Each of the high-frequency and high-amplitude signal detection unit 3 and the first light modulation element control value correction unit 5 has an internal storage unit and stores modulation element control values for one frame. Only the three lines including it may be stored in the internal storage unit. In this case, the modulation element control value is stored in the internal storage unit, and at the same time, the modulation element control unit of the pixel to be processed is read, and whether or not it is a correction target pixel is detected and corrected.

As a result of the above-described processing, as shown in FIG. 8, the image formation state on the second light modulation element differs depending on the color. Therefore, even if no moire occurs in a state where a solid image is displayed, it is When a high-frequency, high-amplitude image in which black and white appear alternately can be suppressed, a phenomenon in which new moire occurs.
That is, as can be seen from FIG. 9C, this moire is likely to occur when the pixels of the second light modulation element 9 have high transmittance and the transmittance of adjacent pixels is low. This is because a part of the emitted light emitted from the corresponding pixel of the first light modulation element 7 spreads and is shielded by the low transmittance pixel of the adjacent second light modulation element 9. At this time, the transmittance of the pixel of the first light modulation element 7 corresponding to the pixel that is shielded by the second light modulation element 9 is also set to a low value as can be seen from FIG.

Therefore, by increasing the transmittance of the pixel of the first light modulation element 7 corresponding to the pixel of the second light modulation element 9 blocking the spread light as in this embodiment, the adjacent transmittance is high. The amount of light transmitted through the pixel increases, and a part of the light transmitted through the pixel of the first light modulation element 7 corresponding to the pixel of the second light modulation element 9 having high transmittance is adjacent to the second light with low transmittance. The amount of light reduced by the pixel of the modulation element 9 can be compensated.
Therefore, when the transmittance of the search pixel of the second light modulation element 9 is sufficiently lower than the transmittance of the adjacent pixels, that is, smaller than the ratio measured in advance by actual measurement, the first light modulation element corresponding to this search pixel 7 by changing the transmittance of the pixel 7 to the first light modulation element control value of the pixel of the first light modulation element 7 of the first light modulation element 7 corresponding to the comparison pixel, thereby increasing the high frequency and high amplitude. Moire generated when an image is displayed can be suppressed.

Further, in the above embodiment, the comparison pixel T24 having the highest transmittance, that is, the highest control value among the pixels adjacent to the detection pixel P2 in the second light modulation element 9 as the control value of the correction target pixel P1. The control value of the pixel T14 of the first light modulation element 7 corresponding to is adopted.
However, in the first light modulation element 7, the control value of the pixel having the highest transmittance (ie, control value) among the pixels adjacent to the correction target pixel is detected, and the control value is adopted as the control value of the correction target pixel. As such, the first light modulation element control value correction unit 5 may be configured. At this time, the process of detecting the correction target pixel from the comparison of the transmittance between the detection pixel P2 and the adjacent pixel is the same as that of the embodiment already described.

<Second Embodiment>
Next, the image display apparatus according to the second embodiment will be described with reference to FIG. FIG. 5 is a block diagram illustrating a configuration example of the image display device according to the second embodiment. In the image processing apparatus according to the second embodiment shown in FIG. 5, the same components as those in the first embodiment shown in FIG.
The difference from the first embodiment of FIG. 1 is that the high-frequency, high-amplitude signal detection unit 3 corrects the first light modulation element control value for each color component of the input video signal (R, G, B). This is to detect a correction target pixel. Here, the correction target pixel detection method is the same as in the first embodiment.

The first light modulation element control value correction unit 5 also controls the first light modulation element control value of the correction target pixel in the first light modulation elements 7R, 7G, and 7B for each color component detected by the high frequency, high amplitude signal detection unit 3. Is to correct.
Here, the search processing of the correction target pixel by the high frequency high amplitude signal detection unit 3 and the correction processing of the first light modulation element control value of the correction target pixel by the first light modulation element control value correction unit 5 are R, G , B, except for each color component, the same as in the first embodiment already described.
Further, the first light modulation element 7 in the first embodiment modulates the light of the color component in the second embodiment, so that the first light corresponds to the color components of R, G, and B, respectively. There are three modulation elements 7R, 7G, and 7B.

For this reason, the high-frequency, high-amplitude signal detection unit 3 needs to detect a correction target pixel in each of the first light modulation elements 7R, 7G, and 7B.
For this reason, threshold tables 4R, 4G, and 4B corresponding to the respective color components for determining whether or not correction is necessary corresponding to the search pixel are provided, and the high-frequency and high-amplitude signal detection unit 3 includes the first Detection of the correction target pixels corresponding to each of the light modulation elements 7R, 7G, and 7B is performed corresponding to the search pixel of the second light modulation element 9 using the threshold value tables 4R, 4G, and 4B, respectively.
Each of the first light modulation element driving units 6G, 5G, and 6B corresponds to the first light modulation element control value for each of the first light modulation elements 7R, 7G, and 7B input from the first light modulation element correction unit 5. Thus, the transmittance of each pixel of the first light modulation elements 7R, 7G, and 7B is controlled.
Thereby, in addition to the effect of 1st Embodiment, the image display apparatus of 2nd Embodiment sets the light quantity which injects into the 2nd light modulation element 9 with respect to each color component of R, G, B. Therefore, the generation of moire in full color HDR can be suppressed with high accuracy.

Next, FIG. 6 shows a configuration of a projector using the image display apparatus according to the second embodiment of FIG.
In FIG. 6, the light source device 10 that emits the illumination light L, the uniform illumination system 20 that equalizes the luminance distribution of the illumination light L emitted from the light source device 10, and the illumination light as red illumination light, green illumination light, and blue color. A spectral system 30 (spectral means) that splits the illumination light and guides the illumination light, and first light modulation elements 7R, 7G, and 7B that are installed for the illumination light and modulate the luminance of the illumination light. A cross dichroic prism 50 that synthesizes illumination light (modulated light) that has undergone luminance modulation in each of the first light modulation elements 7R, 7G, and 7B and emits the combined light, and a relay lens 60 that guides the combined light (both sides) A telecentric lens), a second light modulation element 9 for luminance-modulating the synthesized light emitted from the relay lens, and a projection for enlarging and projecting the synthesized light modulated by the second light modulation element 9 onto the screen 200 Lens 100 and a (projection unit) and.

  In addition, the function in the 1st light modulation element control value determination part 1, the 2nd light modulation element control value determination part 2, the high frequency high amplitude signal detection part 3, and the 1st light modulation element control value correction | amendment part 5 in FIG. The image display control process may be performed by recording a program for recording on a computer-readable recording medium, causing the computer system to read and execute the program recorded on the recording medium. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer system” includes a WWW system having a homepage providing environment (or display environment). The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

It is a block diagram which shows the structural example of the image display apparatus by the 1st Embodiment of this invention. It is a conceptual diagram which shows the structure of the threshold value table memorize | stored in the threshold value table memory | storage part 4 in FIG. It is a conceptual diagram which shows a response | compatibility of the pixel of the 1st light modulation element 7 and the 2nd light modulation element 9 explaining the detection process of a correction target pixel. It is a conceptual diagram which shows a response | compatibility of the pixel of the 1st light modulation element 7 and the 2nd light modulation element 9 explaining the detection process of a correction target pixel. It is a block diagram which shows the structural example of the image display apparatus by the 2nd Embodiment of this invention. It is a conceptual diagram which shows the structure of the projector using the image display apparatus by the 2nd Embodiment of this invention. 5 is a graph showing transmittance control values in a first light modulation element 7 and a second light modulation element 9. It is a conceptual diagram explaining the mechanism in which a moire generate | occur | produces with the image apparatus by 2 modulation | alteration optical system. It is a conceptual diagram explaining the mechanism in which a moire generate | occur | produces with the image apparatus by 2 modulation | alteration optical system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light modulation element control value determination part 2 ... 2nd modulation element control value determination part 3 ... High frequency high amplitude signal detection part 4, 4R, 4G, 4B ... Threshold table memory | storage part 5 ... 1st light modulation element control value correction | amendment part 6 ... 1st light modulation element drive part 7, 7R, 7G, 7B ... 1st light modulation element 8 ... 2nd light modulation element drive part 9 ... 2nd light modulation element 9

Claims (9)

The first light modulation element and the second light modulation element arranged at the subsequent stage of the first modulation element are optically arranged in series in units of pixels, and each of the transmission elements corresponds to the input image signal. A two-modulation optical image display device that displays an image by controlling a rate,
A first light modulation element control value determining unit for obtaining a first light modulation element control value for driving the first light modulation element by the image signal;
A second light modulation element control value determining unit for obtaining a second light modulation element control value for driving the second light modulation element by the image signal;
From the second light modulation element control value, a pixel having a relatively low transmittance is detected in a region where the pixel having a different transmittance changes in a high-frequency high-amplitude state where the pixels appear alternately, and the pixel corresponding to this pixel is detected. A high-frequency, high-amplitude signal detector that uses a pixel of the first light modulation element as a correction target pixel;
A first light modulation element control value correction unit that corrects the first light modulation element control value of the correction target pixel in accordance with the transmittance of other pixels in the region;
A first light modulation element driving unit for driving the first light modulation element according to the corrected first light modulation element control value;
An image display apparatus comprising: a second light modulation element driving unit that drives the second light modulation element by the second light modulation element control value.   The high-frequency, high-amplitude signal detection unit detects the correction target pixel by comparing the transmittance between the detection target pixel and a pixel adjacent to the detection target pixel. 1. The image display device according to 1.   When the high-frequency, high-amplitude signal detection unit detects a correction target image, a threshold value is set corresponding to the ratio of the transmittance between the second light modulation control value of the pixel to be detected and the pixel adjacent to the pixel. The image display apparatus according to claim 2, wherein:   When the high-frequency, high-amplitude signal detection unit detects that the control value of any of the adjacent pixels exceeds the threshold corresponding to the control value of the detection target pixel, the detection target pixel is set as a correction target pixel. The image display device according to claim 3. A threshold value table indicating a correspondence relationship between the second light modulation element control value and a threshold value for the second light modulation element control value;
The ratio of the transmissivity at the time when moire can no longer be visually recognized by displaying an image in a high-frequency, high-amplitude state in which white and black display pixels are adjacent to each other, and increasing the transmissivity of the adjacent black display pixels by a certain width. The reference transmittance is obtained by multiplying the transmittance corresponding to each second light modulation element control value by the reciprocal of the ratio, and the second light modulation element control value corresponding to this reference transmittance is obtained as the threshold value. The image display device according to claim 4, wherein the image display device is used as a display device.   The first light modulation element control value correction unit corresponds to the first light modulation element corresponding to the pixel having the highest transmittance among the pixels adjacent to the detection target pixel, as the first light modulation element control value of the correction target pixel. The first light modulation element control value is changed to a first light modulation element control value of a pixel of the first pixel, or is changed to a first light modulation element control value of a pixel exhibiting the highest transmittance in a pixel adjacent to the correction target pixel. The image display device according to claim 5.   The high-frequency, high-amplitude signal detection unit performs correction processing of a correction target pixel using “0” as a control value of a virtual pixel when there is no adjacent pixel in a pixel on the outer peripheral portion of the image. The image display device according to any one of claims 1 to 6. When the first modulation element is provided for each of the R, G, and B color components,
The image display apparatus according to claim 1, wherein the high-frequency, high-amplitude signal detection unit detects a correction target pixel for each of R, G, and B color components. An image display device according to any one of claims 1 to 8,
Projector for projecting modulated light emitted from the image display device onto a screen.

Images